Experiments are designed to: (1)\establish primary cultures of endothelium derived from capillaries of selected embryonic rudiments, fetal organs and selected adult sources; (2)\produce and identify marker reagents for these endothelial cells to help detect and characterize endothelial cells in general, and tissue or organ-defined capillary endothelial subpopulations more specifically; (3)\analyze the process of tumor-induced and lymphocyte-induced angiogenesis as this may be reflected differentially or in common for the capillary endothelial cells derived from the various sources; (4)\initiate developmental studies aimed at determining the role of endothelial cells in selective cell adhesion; and (5)\initiate developmental analysis of the morphogenesis of mouse capillaries during mouse embryogenesis. It is hoped that the outlined research will lead to a better understanding of the developing vascular system and, more specifically, that it will provide new insight into the neovascular process that accompanies the development and metastatic spread of tumors and that is in obligatory association with the inflammatory process.